MSDN Magazine - October 2007 - (Page 133)

Describing the EEK!-osystem STANLEY B. LIPPMAN I n the previous installment of this column, I began A Scent building my mouse and mouse environment simulation called EEK! I discussed the two primary methods of parsing the environment XML file: the firehose and Nesting Site Document Object Model (DOM). This month I’ll begin by crafting the XML document, then I’ll show you Food/Water another way of incorporating an XML file into the proE-shock {Pain} gram: using a DataSet, found within the System::Data namespace of the .NET Foundation Class Library. The DataSet leverages the document as a set of relational taA Burr {Annoyance} bles that you can traverse using unique key values. The first order of business is generating a description Figure 1 Neutral World Tile Attributes of the simulated environment to allow the program to reconstruct and manipulate that world in the course of the ap- the entities it finds) and allows it to identify and value subsequent plication. To do this, I need to determine how best to design the areas of the environment by recognizing similar patterns. There XML document to represent the terrain the mouse will inhabit in are five colors associated with four valuations. the simulation. Green and dark blue indicate a rewarding experience—food and The environment I’ve created (if you’re not familiar with it, drink, a nesting site, and so on. Bright blue denotes fear—some please read the June 2007 column at msdn.microsoft.com/msdnmag/is- terrifying encounter (in this case represented by simulated electrisues/07/06/NettingC) has a unique constraint. I need to be able to cal shock). Red signifies anger or frustration—some obstruction represent it at both macro- and micro-scales and to be able to slide to the mouse’s goal-seeking (embodied in what I call burrs). And up and down examining the state of each simultaneously—that is, orange represents a neutral experience. within the Tick of the simulator. For example, at the micro level, One panel of the simulation’s display shows the real-time colorI want to track the movement of chemical molecules within the ing of the environment as it unfolds. Because the environment is environment (the smell of different entities, such as food or a cat). deliberate, the resulting maps and ability of the mouse to reach its At the macro level, I need to track the resulting progress and ac- goals should be predictable based on its configured nature. tions of the mouse. A good part of a mouse’s behavior is driven by In practical terms, this means there is one “truth” map and one chemical molecules that trigger associated program functions be- subjective map for each moving (sentient) entity in the simulation. cause, unlike humans, it depends on smell, not sight, for exploring The truth map is built from the XML document and represents the its environment. I call this a Scalable Environment Map, or SEM. physics of the simulated environment. Each subjective map is built up by exploration and colored by personal experience. It is always Hazards and Rewards in the Environment a subset of the “truth” map. The initial quest driving the mouse is The simulated environment itself is just a mapping, although it to mark off a personal territory through its subjective map, which contains both hazards and rewards. It represents a contiguous area contains food and water and a nesting site, and which it can dethat the mouse moves through, encountering memorable entities fend. Until I populate the simulation with multiple sentient entities such as nesting sites, food, burrs, electrical shocks (e-shocks), scents, competing for territory, the burrs and e-shocks of the environment and so on (see Figure 1). These encounters between the mouse and will represent hazards and constraints. Figure 1 gives a sense of how the environment literally color the environment. a world tile of the environment is populated. In the simulation, the experience of the mouse in exploring its The environment is separated into tiles that are connected by environment is “remembered” by maintaining a personal map. In from one to four “doortos” that represent entrances and exits availthat map, which begins as a blank, a color represents how the mouse able to the mouse. The simulation begins in an initial chamber experienced that portion of the environment (its interactions with that has three doortos representing alternative paths. This chamoctober2007 133 http://msdn.microsoft.com/msdnmag/issues/07/06/nettingc http://msdn.microsoft.com/msdnmag/issues/07/06/nettingc

Table of Contents Feed for the Digital Edition of MSDN Magazine - October 2007

Cover Contents Toolbox CLR Inside Out Basic Instincts Data Points Cutting Edge Pooled Threads WPF Threads Parallel Linq Parallel Performance Mobile Apps Test Run Foundations Windows with C++ Netting C++ .NET Matters { End Bracket } Net Nuptials

MSDN Magazine - October 2007

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